Created attachment 1720415 [details]
dmesg

i915: External display periodically shuts off/loses connection with all kernels after 5.6.13-300.fc32.x86_64

1. Please describe the problem:

External display periodically shuts off/loses connection with all kernels after 5.6.13-300.fc32.x86_64. (Dell Latitude 5480)

Problem hardware:
Dell Latitude 5480 (Mesa Intel® HD Graphics 620 (KBL GT2), newest bios/fw 1.17.1) + Dell UltraSharp U2719DCE Monitor

Unable to reproduce with other Laptop, Lenovo ThinkPad L480 (Mesa Intel® HD Graphics 620 (KBL GT2)),

It can happen several times a minute.

It can also stay connected for a longer period, but then shut down/lose connection.

Built-in laptop screen works as expected.

Sidenote: built-in laptop screen can flicker during boot password/plymouth (with or without the external screen connected)

Can reproduce this with Fedora 33 beta Live and Ubuntu 20.04, but i field it here since i manage to track down the exact kernel the problems occurs with.

2. What is the Version-Release number of the kernel:

5.6.14-300.fc32.x86_64+


3. Did it work previously in Fedora? If so, what kernel version did the issue
   *first* appear?  Old kernels are available for download at
   https://koji.fedoraproject.org/koji/packageinfo?packageID=8 :

5.6.14-300.fc32.x86_64

4. Can you reproduce this issue? If so, please provide the steps to reproduce
   the issue below:

Boot with kernel 5.6.14-300.fc32.x86_64 and connect the external display

5. Does this problem occur with the latest Rawhide kernel? To install the
   Rawhide kernel, run ``sudo dnf install fedora-repos-rawhide`` followed by
   ``sudo dnf update --enablerepo=rawhide kernel``:

No fedora kernel after 5.6.14-300.fc32.x86_64 works.

6. Are you running any modules that not shipped with directly Fedora's kernel?:

No, can reproduce with LiveDVD

7. Please attach the kernel logs. You can get the complete kernel log
   for a boot with ``journalctl --no-hostname -k > dmesg.txt``. If the
   issue occurred on a previous boot, use the journalctl ``-b`` flag.

$ for i in /sys/module/i915/parameters/*;do echo ${i}=`cat $i`;done > 5.6.13.log
/sys/module/i915/parameters/alpha_support=N
/sys/module/i915/parameters/disable_display=N
/sys/module/i915/parameters/disable_power_well=1
/sys/module/i915/parameters/dmc_firmware_path=(null)
/sys/module/i915/parameters/edp_vswing=0
/sys/module/i915/parameters/enable_dc=-1
/sys/module/i915/parameters/enable_dpcd_backlight=-1
/sys/module/i915/parameters/enable_dp_mst=Y
/sys/module/i915/parameters/enable_fbc=1
/sys/module/i915/parameters/enable_guc=0
/sys/module/i915/parameters/enable_gvt=N
/sys/module/i915/parameters/enable_hangcheck=Y
/sys/module/i915/parameters/enable_ips=1
/sys/module/i915/parameters/enable_psr=-1
/sys/module/i915/parameters/error_capture=Y
/sys/module/i915/parameters/fastboot=-1
/sys/module/i915/parameters/force_probe=
/sys/module/i915/parameters/force_reset_modeset_test=N
/sys/module/i915/parameters/guc_firmware_path=(null)
/sys/module/i915/parameters/guc_log_level=-1
/sys/module/i915/parameters/huc_firmware_path=(null)
/sys/module/i915/parameters/invert_brightness=0
/sys/module/i915/parameters/load_detect_test=N
/sys/module/i915/parameters/lvds_channel_mode=0
/sys/module/i915/parameters/mmio_debug=0
/sys/module/i915/parameters/modeset=-1
/sys/module/i915/parameters/nuclear_pageflip=N
/sys/module/i915/parameters/panel_use_ssc=-1
/sys/module/i915/parameters/prefault_disable=N
/sys/module/i915/parameters/reset=3
/sys/module/i915/parameters/vbt_firmware=(null)
/sys/module/i915/parameters/vbt_sdvo_panel_type=-1
/sys/module/i915/parameters/verbose_state_checks=Y

$ diff 5.6.13.log 5.6.14.log
14c14
< /sys/module/i915/parameters/enable_psr=0
---
> /sys/module/i915/parameters/enable_psr=-1

$ diff 5.6.13.log 5.8.10.log
1d0
< /sys/module/i915/parameters/alpha_support=N
29d27
< /sys/module/i915/parameters/prefault_disable=N